1. Field of Invention
The present invention relates to light emitting diode (LED) substrate.
2. Description of Related Art
A conventional LED substrate is generally imprinted with a nano-patterned sapphire substrate technology to form a nano-pattern thereon, so as to increase light extraction efficiency. The nano-patterned sapphire substrate technology often uses a nanoimprint lithography process because such process is simple and quick and suitable for use in industrial production.
A concave portion of the nano-pattern formed by a conventional method for manufacturing a LED substrate does not have a sufficient depth, thus leading to unsatisfactory light extraction efficiency. FIG. 1 is a schematic diagram showing a light extraction effect within a conventional light emitting diode structure. A conventional light emitting diode structure has a conventional substrate 600 and a light emitting multi-layer structure 500. Depths of concave portions formed on the conventional substrate 600 may only reach to 300 nm, thus limiting the improvement of brightness. Because the depths of the concave portions formed on the conventional substrate 600 are not deep enough, after being generated by the multiple-layer-emitting structure 500, the light passes through the conventional substrate 600 along a direction 700 and resulting brightness reduction.